“The pair looked at one another.”

No, they didn’t.

Editing is often intuitive. I could tell you, for instance, which usage is correct, but I couldn’t tell you why. It came up with a project and I got curious. Then I went to the Chicago Manual of Style. Here’s why for this one:

When two people are involved, the best way to write it is, “They looked at each other.” When it’s more than two people (or things, for that matter) use “one another.”

The distinction becomes clearer with things: “His eyesight was so poor that when he looked to the bowling pins standing at the end of the lane, they were just a soft white mass. Dave couldn’t distinguish one from another.” (That’s right.)

“Each other” in a group hits the reader’s eyes and ears wrong and they may not know why. (This is one reason reading aloud as you edit can be such a powerful trick of the trade.)

It’s not a big deal unless you’re a word nerd or getting paid to edit something. However, usually, if you write a passage that hits the reader wrong or makes them go back, there’s something quirky there that needs another look.